Perhaps something as simple as this: 
my $id_file = 'id.txt';
my %id;
open my $ID, "<", $id_file or die "Error opening $id_file $!";
while (<$ID>) {
    chomp;
    $id{$_} = 1;
}
close $ID;

while (<>) { # assumes file 2 is passed to the script - to be adjusted
+ to real conditions
    my $key = $1 if /^(\w+)/;
    print if exists $id{$key};
}

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In reply to Re: Extracting lines starting with a pattern from an array by Laurent_R
in thread Extracting lines starting with a pattern from an array by Alessandro

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